Uses and Effectiveness of Triclosan
- Triclosan is used in consumer products such as toothpaste, soaps, detergents, toys, and surgical cleaning treatments.
- It is also found in kitchen utensils, bedding, socks, and trash bags.
- Triclosan is incorporated in conveyor belts, fire hoses, dye bath vats, and ice-making equipment as an antimicrobial.
- It is used in commercial HVAC coils to prevent microbial growth.
- Triclosan is used in surgical scrubs, hand washes, and coatings for surgical sutures.
- Triclosan coated sutures reduce the risk of surgical site infection.
- Antimicrobial hand soaps containing triclosan provide a slightly greater bacterial reduction compared to plain soap.
- Triclosan/copolymer-containing toothpastes reduce dental plaque and gingival inflammation.
- There is weak evidence of a reduction in tooth cavities.
- Triclosan toothpastes do not cause an increase in serious adverse cardiac events.

Chemical Structure and Properties of Triclosan
- Triclosan is a white powdered solid with a slight aromatic, phenolic odor.
- It is soluble in ethanol, methanol, diethyl ether, and strongly basic solutions.
- Triclosan is a chlorinated aromatic compound with functional groups representative of both ethers and phenols.
- It is slightly soluble in water.
- Triclosan can be synthesised from 2,4-dichlorophenol.

Mechanism of Action and Endocrine Disruption of Triclosan
- Triclosan acts as a biocide with multiple cytoplasmic and membrane targets at high concentrations.
- At lower concentrations, it appears bacteriostatic and inhibits fatty acid synthesis.
- Triclosan binds to bacterial enoyl-acyl carrier protein reductase (ENR) enzyme.
- This binding increases the enzyme's affinity for NAD and prevents fatty acid synthesis.
- Vertebrates are not affected by this mode of action.
- Triclosan is a weak endocrine disruptor.
- It binds with low affinity to both the androgen receptor and the estrogen receptor.
- Agonistic and antagonistic responses have been observed.
- The relevance of this to humans is uncertain.

Distribution, Metabolism, and Elimination of Triclosan
- Triclosan is metabolised by humans primarily through conjugation reactions into glucuronide and sulfate conjugates.
- These conjugates are excreted in feces and urine.
- Pharmacokinetic studies show that triclosan sulfate and glucuronide are formed in the liver at approximately equal rates.
- At concentrations below 1 microMolar, sulfonation is the major metabolic pathway for elimination.
- Triclosan concentrations of 1 to 5 microMolar are considered environmentally relevant.

Health Concerns and Environmental Impact of Triclosan
- Triclosan has been designated as a contaminant of emerging concern (CEC) by the United States Geological Survey.
- Potential health concerns include antimicrobial resistance and endocrine disruption.
- Triclosan is thought to accumulate in wastewater and return to drinking water, causing increasing effects with ongoing use.
- The FDA ruled that triclosan is not generally recognised as safe and effective.
- Triclosan is under investigation for public health risk.
- Triclosan has been associated with a higher risk of food allergy.
- Exposure to bacteria may reduce allergies, leading to the association with triclosan.
- Triclosan has been linked to allergic contact dermatitis in some individuals.
- Triclosan concentrations have been associated with allergic sensitization to inhalant and seasonal allergens.
- Triclosan can react with free chlorine in chlorinated tap water, producing other compounds like 2,4-dichlorophenol.
- Some of these intermediates can convert into dioxins upon exposure to UV radiation.
- Triclosan has been detected in human breast milk, blood, and urine samples.
- Triclosan exposure in rats has been shown to modulate estrogen-dependent responses.
- Triclosan possesses (anti)estrogenic and (anti)androgenic properties depending on species, tissues, and cell types.
- Prenatal triclosan exposure has been associated with increased cord testosterone levels in infants.
- Triclosan is persistent in the environment and can accumulate in water, sediment, and organisms.
- Can be toxic to aquatic life, especially algae and fish.
- May contribute to the development of antibiotic resistance in bacteria.
- Can undergo transformation during wastewater treatment, leading to the formation of potentially harmful byproducts.
- Triclosan has been detected in human urine, blood, and breast milk, raising concerns about human exposure.
- Studies suggest that triclosan may disrupt hormone function and affect reproductive and developmental processes.
- Animal studies have shown potential carcinogenic and endocrine-disrupting effects.
- Some studies suggest a link between triclosan exposure and allergies, asthma, and other respiratory conditions.
- Triclosan has been associated with changes in gut microbiota and immune system function.
- The FDA has banned triclosan in over-the-counter consumer antiseptic washes due to lack of evidence for its effectiveness and concerns about its safety.
- Triclosan-coated sutures have been used to reduce the risk of surgical site infections.
- The CDC has included a recommendation for the use of triclosan-coated sutures in surgical procedures.
- Studies have shown that triclosan-coated sutures can effectively reduce the incidence of surgical site infections.
- Triclosan has been used in healthcare facilities to control and prevent the spread of antibiotic-resistant bacteria like MRSA.
- Guidelines for the use of triclosan in healthcare facilities have been developed to ensure proper and safe use.